Machinery safety

Machinery Safety

Risk Assessement and Risk Reduction of Machines

GT Engineering is specialised in the risk Assessement and risk Reduction of Machines, Production Lines and Processes. 
They performed several risk Analysis of Continuous Casting Machines, Rolling Mills, and Electric Arc Furnaces.
We work very close with Transfer Machine Manufacturers and, in general, Assembly Machine Producers.
We have experience in very different Industries: from Textile to Laser Cutting to Sputtering processes used in the semiconductor sector.
We regularly participate to the Technical Commettes liased with CENELEC and CEN, responsible for publication of the main Machinery Safety Technical Standards.

Industrial control panels and the door Interlock
Shall a Basic Safety Standard be applied to machineries? The case of pink functional grounding cable
Technical Standards Terminology
Guide to application of the Machinery Directive 2006/42/EC
Safeguarded Space
Whole Body access
CE Marking of Control Panels
Reduced Speed or Reduced Energy
Safety in Collaborative Robotics
The emergency stop function
Why Machinery safety is so important?
Machinery Safety for Continuous Casting of Steel
Machinery Directive: the Harmonised Standards
The Alarp Principle
CE Marking of Machineries made in North America
Machinery Safety in USA
EN 13849-1 and the functional safety
Product Standard for Industrial Control Panels

Among the commands of a machine, probably, the emergency stop is the most visible one; however it is not the easiest to understand.

The reference standard is the ISO 13850, whose latest edition was published in November 2015: "Safety of machinery - Emergency Stop Function – Principles for design".

The definition is (§3.1): ”function which is intended to avert arising or reduce existing hazard to person, damage to machinery or to work in progress; and be initiated by a single human action”.

In this article some important aspects are discussed; Please refer to the standard to understand all the requirements and for a correct implementation of the function.

Is an enclosure interlocking required for industrial control panels? That is a strongly debated topic and not yet fully understood: let's clear this out.

Should the Reset button in a machinery be handled by a safety module, or can it be one of several inputs to the Automation PLC?

The question can be rewritten in a more correct language by asking if the Reset is a Safety Function.

IEC 60204-1 VS IEC 60445: green-and-yellow functional grounding conductor VS pink functional grounding conductor.

Are you new in the Machinery Technical Standard world and do you feel a bit lost with the terminology?

  The Guide to the Machinery Directive 2006/42/EC has been updated in October 2019. It contains a number of clarifications and corrections to the concepts of “safety components” and “partly completed machinery”, and some edits to ensure coherence with the Low Voltage Directive (LVD) Guide. There are also two new paragraphs about the machinery control units (§417) and safety components which are considered to be logic units (§418).  In the Attachments section of this page you can download the 2019 Guide to the New Machinery Directive 2006/42/EC.  
Machinery safety

Often the manufacturer has doubts about what should be indicated in the Instruction manual.
One of the aspects is whether it is necessary to report the spare parts list. What obligation does the manufacturer have in this regard?

The drawing up machinery instructions is an obligation of the manufacturer. Point 1.7.4 of the Machinery Directive 2006/42/EC deals with the obligations to be met regarding the Instructions for Use, before the machine is placed on the market and/or put into service.

RESS details the contents of the instructions for safe use of the machine. The letter t) specifies that the User Manual must contain:

t) the specifications of the spare parts to be used, when these affect the health and safety of operators; 

The following is defined in the Guideline of Directive 2006/42/EC:

“Section (t) refers to information about spare parts. In general, the supply of spare parts and the supply of a spare parts list are not covered by the provisions of the Machinery Directive and is thus a matter for contractual agreement between the manufacturer and the user. However, where parts subject to wear and tear need to be replaced in order to protect the health and safety of users, the specifications of the appropriate spare parts must be given in the instructions.

Examples of such spare parts include: 
•    guards for removable mechanical transmission devices;
•    flexible guards subject to wear and tear;
•    comments on section;
•     filters for systems to provide clean air to operating positions;
•    load bearing components on lifting machinery;
•    guards and their fixing systems used to retain ejected objects or parts of machinery.” 

Therefore, the spare parts list is mandatory to issue the CE certification of a machine if they are parts subject to wear and that could affect the safety.

Before placing machinery on the market and/or putting it into service, the manufacturer shall draw up the EC Declaration of conformity in accordance with Machinery Directive 2006/42/EC.  When a machine, that falls within the scope of the Machinery Directive, has an electrical supply within the voltage limits of the Low Voltage Directive (between 50 and 1000 V for alternating current or between 75 and 1500 V for direct current), it must fulfil the safety objectives of the Low Voltage Directive. However, the EC Declaration of Conformity should not refer to the Low Voltage Directive. Annex I of Directive 2006/42/EC: 1.5.1 Electricity supply “Where machinery has an electricity supply, it must be designed, constructed and equipped in such a way that all hazards of an electrical nature are or can be prevented. The safety objectives set out in Directive 73/23/EEC shall apply to machinery. However, the obligations concerning conformity assessment and the placing on the market and/or putting
Machinery safety is often dealing with 2 areas: -    A safe area, free of hazards -    A dangerous one Historically, the term used to identify the dangerous area is “Hazard Zone” ISO 12100 definition: 3.11 Hazad Zone (danger zone): any space within and/or around machinery in which a person can be exposed to a hazard. Link to the concept of hazard zone is the term Safeguard and Safeguarding (ISO 12100, definitions) 3.26 Safeguard: guard or protective device 3.21 Safeguarding: protective measures using safeguards to protect persons from hazards which cannot reasonably be eliminated or risks which cannot be sufficiently reduced by inherently safe design measures. The Safeguards (for example, Interlocking devices, Pressure Sensitive devices, Guards…) are used to separate the safe area from the dangerous one. Instead of Hazard zone, the term that is now used and that will replace Hazard Zone is Safeguarded Space. One of the first standards to adopt the term was ISO 10218-2: 3.13.3 Safeguar
Machinery safety


According to

EN 60204-1 "Safety of machinery - Electrical equipment of machines Part 1: General requirements",

there are three categories of stop functions:


  • Stop Category 0: stopping by immediate removal of power to the machine actuators (i.e. an uncontrolled stop);
  • Stop Category 1: a controlled stop with power available to the machine actuators to achieve the stop and then removal of power when the stop is achieved;
  • Stop Category 2: a controlled stop with power remaining available to the machine actuators.

    These three categories are taken from specific standards such as ISO 13850 and IEC 61800-5-2.
THE QUESTION The manufacturer often asks questions about the free circulation of machines in countries outside the EU.  Do the same EU principles apply to Turkey? CONSIDERATIONS The Machinery Directive applies to machinery or partly completed machinery placed on the EU market. It does not apply to products manufactured in the EU with a view to being placed on the market or put into service in countries outside the EU, although certain of these countries may have national regulations based on the Machinery Directive or accept machinery on their market that complies with the Directive. There are countries outside the EU, such as Turkey, which allow free movement in case the machine carries the CE mark. The following is defined in the Guideline of Directive 2006/42 / EC: "By virtue of the Agreement on the European Economic Area (EEA), machinery and partly completed machinery that complies with the Machinery Directive also benefits from free movement in Iceland, Liechtenstein and Norwa
If you deal with Machinery Safety you may wonder what Whole Body Access means. That is a relatively new terminology (this article was written in 2019). It indicates the risk that a person remains inside a safeguarded space. Exposure to a hazard represents a potential risk when a person gains access to a hazard zone beyond a safeguard space.   A hazard arises when the person is no longer detected and the hazardous situation machine function resumes while a person is still within the safeguarded space.  Whole body access is often associated with the concept of providing protection around the perimeter of a hazard zone, such that a person could enter the hazard zone beyond the perimeter of protection.   Whole body access also occurs when a safeguard is located at a separation distance from the hazard zone and persons are not detected between the safeguard and the hazard zone.  For whole body access, both of the following parameters shall be considered:  1) an opening defined by the phy
The CE marking indicates the conformity of the product with the Union legislation applying to the product and providing for CE marking. The CE marking is affixed on products that are placed on the EEA and Turkish market, whether they are manufactured in the EEA, in Turkey or in another country. The CE marking is a key indicator (but not proof) of a product’s compliance with EU legislation and enables the free movement of products within the European market. The CE marking indicates that a product complies with all the applicable EHSRs (Essential Health and Safety Requirements) of all the applicable Product Directives. The CE marking is the visible consequence of a whole process comprising conformity assessment in a broad sense and indicates that a product is declared by the manufacturer as in conformity with Union harmonisation legislation.

The assessment and risk reduction process is detailed in various standards.
An important aspect of the risk reduction methods suggested by the standards concerns the reduction of energy levels.

When possible, access to a segregated area should be carried out at zero energy with the elimination and isolation of hazardous energy (preferred method to reduce the risk). However, some activities require partial or total energization to be performed and to operate machine elements with disabled protection devices. For these specific activities, reduced energy operating modes are are a way to reduce the risk for the operator or the maintenance person.

Some types of machines are subject to specific standards  that define the operating modes in terms of reduced energy values and other additional conditions. 
However, many others, are not covered by a specific standard and therefore manufacturers may not know what threshold to use. 

Here we present some values stated in technical standards, grouped in the following way:

- Speed (mm / s): to be used in case of objects that move at constant speed (Robot arm).

- Force (N): in case of constant pressure without acceleration of the element.

- Kinetic Energy (J): to be used in case of objects that move at increased speed (a gate/protection falling from a certain hight).

- Pressure (N / cm2). In case certain part of the body is subject to the possible damage.

There is no “Collaborative Robot”. That is one of the first statements you hear from people working in Collaborative Robotics. The reason is because the robot can be designed for a collaborative task, but it is the Application that makes the “Robot Collaborative”. The reference standard for Collaborative Application is  ISO/TS 15066:2016 - ROBOTS AND ROBOTIC DEVICES -- COLLABORATIVE ROBOTS Not only for the unfortunate title, the standard will be included in the new edition of 2 important standards on Robots: ISO 10218-1: Robotics — Safety requirements for robot systems in an industrial environment — Robots ISO 10218-2: Robotics — Safety requirements for robot systems in an industrial environment — Robot systems and integration In September 2019 both standards were at CD Stage. They now fully include requirements for Collaborative Applications. For example in ISO 10218-1: 5.14 Requirements for robots having safety functions to enable collaborative applications There are four impo
Among the commands of a machine, probably, the emergency stop is the most visible one; however it is not the easiest to understand. The reference standard is the ISO 13850, whose latest edition was published in November 2015: "Safety of machinery - Emergency Stop Function – Principles for design". The definition is (§3.1): ”function which is intended to avert arising or reduce existing hazard to person, damage to machinery or to work in progress; and be initiated by a single human action”. In this article some important aspects are discussed; Please refer to the standard to understand all the requirements and for a correct implementation of the function.
Machinery Safety is probably the main leverage that can reduce the number of deaths and injuries in the work place. In the European Union machinery is a contribuing factor in more then 300.000 injuries involving more than 3 days off work, according to data (2008) from the European Commission. In China, 30% of Injuries treated in hospital emergency departments are machinery related (data from 2011). Annually there are 65.000 injuries involving days away from work in USA (2012) and 15.000 injuries in Canada. Finally in Australia, in 2013, there have been 3.500 hospitalisations from machiery-related injuries. Machinery safety is best applied during the concept phase of the Machine Development. That is why the most effective legislations identify the manufacturer as the main player that guarantees the safety of its product: those are the Machinery Directive and the Australian Occupational Health and Safety law. In other terms, the importance of inherently safe design was recognised by a
Steel is the world's largest recycling system. Steel used in everyday life can be melted down to become new steel products. In one shell, scrap is preheated using natural gas, while in the other shell, scrap is melted using electric and chemical energy. Then, the molten steel is tapped into ladles. At the ladles metallurgy furnaces, steel chemical composition and temperature is fine-tuned. Alloying elements are added, the carbon content is regulated, and the sulfur level is reduced. Some steel types also are vacuum treated to remove hydrogen and nitrogen. The hot steel is turned into slabs by continuous casting. in an open, water-cooled, copper mould. The Brescia Area is famous in Italy for the number of mini mills. GT Engineering has run a few analysis of Continuous casting process safety, based also upon the C type Harmonised Norm EN 14753. The activities were similar, however the solutions had to be tailored to the specific situation: no one size fits all exists in this fi
Standards in Europe date back to the late 1800s. The International Electro technical Commission (lEC) was founded in 1906 to establish safety specifications for energy and electrical products and protect consumers and the environment. lEC standards are prepared with consultation from technical committees (TC) in over eighty countries. These committees have representation from many interested parties, including, but not limited to, manufacturers, authorities, notified bodies, and consumer groups. Another objective of the lEC is to provide a common reference for international trade through standards. This goal of one set of universally recognized standards is fast becoming a reality for worldwide product acceptance. The concept of European Conformity (CE marking) revolves around European harmonized standards as the minimum requirements for product design and assessment. Strict adherence to these technical specifications should be the focus of all designers and manufacturers. Manufacture
The Alarp principle recognizes that there are three broad categories of risks: 1. Negligible risk: Broadly accepted by most people as they go about their everyday lives, these would include the risk of being struck by lightning or of having brake failure in a car. 2. Tolerable risk: We would rather not have the risk but it is tolerable in view of the benefits obtained by accepting it. The cost in inconvenience or in money is balanced against the scale of risk and a compromise is accepted. This would apply to traveling in a car, we accept that accidents happen but we do our best to minimize our chances of disaster. Does it apply to bungee jumping? 3. Unacceptable risk: The risk level is so high that we are not prepared to tolerate it. The losses far outweigh any possible benefits in the situation. One of the difficult aspects in implementing the ALARP principle is to define the three level of risks. Here the approach from HSE (Health and Safety Executive, in UK). HSE believes that an
If you are a machinery manufacturer or exporter to the European market you might have assumed that shipping products to Europe was a rather simple operation, but found yourself confused by the complex maze of European Conformity laws and regulations. Don't worry, the matter is not so complex. First of all, unless you produce Machineries falling under Annelx IV, you do not need any Notified Body, but a good Consultant on the subject. Second, there is no such thing as a CE approval or CE certification! CE is not a mark or approval, it is a marking which is only a self-declaration under the suppliers' own responsibility. Third, don't be afraid of having to learn the +600 Harmonised EN European Norms that give the presumption of Conformity; for your machinery, you should probably start with less then ten. Of course, to fully deploy the principles and notions of the CE Marking through your organisation is a long walk with sometimes difficult decisions and compromises to be m
Occupational Safety and Health Administration (OSHA) The Occupational Safety and Health Act (OSHA) passed in 1970 to provide safe and healthy working conditions. Part 1910 of the 29th Code of Federal Regulations (CFR) gives specific standards. Subpart O of Part 1910 sets standards for machinery and machine guarding, and divides into Part1910.211 to Part 1910.219. Standard No.   Title 1910.211          Definition 1910.212          General requirements for all machines 1910.213          Woodworking machinery requirements 1910.214          Cooperage machinery 1910.215          Abrasive wheel machinery 1910.216          Mills and calenders in the rubber and plastic industries 1910.217          Mechanical power presses 1910.218          Forging machines 1910.219          Mechanical power-transmission apparatus
Safety standards define safety as freedom from unacceptable risk. The most effective way to eliminate risks is to design them away. But as risk reduction by design is not always possible or practical, safeguarding with static guards are often the next best option, and for several reasons.  Stopping a machine quickly and safely, not only reduces risk but also increases machine uptime and productivity compared with abrupt safety stops. At the same time, the legal obligations are met and the safety of people and the environment is ensured. Functional safety in machinery usually means systems that safely monitor and, when necessary, override the machine applications to ensure safe operation. A safety-related system thus implements the required safety functions by detecting hazardous conditions and bringing operation to a safe state, by ensuring that a desired action, e.g. safe stopping, takes place. The concept of Functional Safety was introduced by the IEC 61508: "Functional Safety of E
THE QUESTION Machine and control panel manufacturers often wonder which Electrical Standard shall they follow for the CE Marking of Industrial Control Panels.  There are different schools of thought: some people think that the IEC 60204-1 Safety of machinery – Electrical equipment of machines – Part 1: General requirements is the only one applicable standard, and others think that IEC 61439-2 Low-voltage switchgear and controlgear assemblies – Part 2: Power switchgear and controlgear assemblies is fully applicable as well. CONSIDERATIONS The doubt is justifiable because neither of the two Standards could be classified as the Product Standard for the industrial control panels.  IEC 61439-2 is the standard for low-voltage switchgears, while IEC 60204-1 provides requirements and recommendations related to the electrical equipment of machines so as to guarantee:  -    Safety of person and property;  -    Consistency of control response;  -    Ease of maintenance.  The latter is more an